1. Field of the Invention
The present invention relates generally to the synthesis and use of novel compositions of matter derived from 9,9-dialkyl fluorene diamine (AFDA). The resultant compositions are unique and are useful in a variety of applications, such as heavy ion radiation shielding components and as components for optical and electronic devices.
2. Description of the Related Art
Fluorene is an important component in materials applications ranging from composite building materials to organic electronics. An important feature of fluorene is that it has two locations, the bridge carbon and the aromatic rings, where various species can be attached. For example, amine groups can be placed on the aromatic rings, such as in the case of the commercially available 2,7-diaminofluorene which is commonly used in the synthesis of larger molecules and polymers.
A problem generally associated with fluorene containing molecules is their insolubility resulting from fluorene being a rigid molecule. Due to the insolubility, the addition of alkyl chains on the fluorene at the nine position (bridge carbon) is a common method for enhancing the solubility of other fluorene containing materials. For example, fluorenes containing borate ester and halogen substitution on the rings commonly contain alkyl chains at the 9 position to enhance solubility. However, the use of alkyl side chains on fluorene diamine has never been demonstrated.
Materials possessing the combined features of structural integrity and shielding against heavy ion radiation (HIR) will be required for future manned space missions. Spacecraft and space habitats are continually bombarded with small amounts of HIR, and in some instances large doses are encountered during certain events such as solar flares. HIR is dangerous to living systems and electronics and must therefore be attenuated to ensure mission safety and longevity. Hydrogen is recognized as the best element for absorbing HIR and high hydrogen content polymers, such as polyethylene, are currently used as shielding materials. However, high hydrogen content polymers are typically not good building materials and can only be used as parasitic cladding. In contrast, aromatic polymers, which contain lower amounts of hydrogen, are good structural materials and could serve as the structural components in spacecraft and space habitats. An ideal material for use in space would be a polymer composition that contains sufficient hydrogen content (aliphatic) for radiation shielding and sufficient aromatic character for structural integrity.